Drafting apparatus



June 30, 1942. J; GRE NLE F 2,287,987

DRAFTING APPARATUS Filed May 28, 1940 /6 glpl llf llllll W44 TERJ G/R ff/VL [AF INVENTQR ATTORNEY Patented June 30, 1942 UNETED STATES aims? PATENT QFiFICE 14 Claims.

This invention relates to drafting appartus, and, more particularly to apparatus of this type including a protractor head or mechanism carrying drawing scales which can be adjusted. to any desired angle.

Drafting apparatus of the protractor head type which has been provided heretofore has been characterized by relatively complicated and expensive means for permitting the adjustment of drawing scales to any of a plurality of angles and the clamping thereof at the desired angle. Further, even in the relatively complicated and expensive apparatus of this type I have found that the apparatus either initially has play due to faulty bearing design and structure or quickly develops play during the normal use of the apparatus. In other words, it is possible to move the end of a drawing scale carried by the drafting apparatus back and forth to an undesirable extent even though the drawing scale is supposed to be clamped tightly in a given position.

It is the general object of my invention to avoid and overcome the foregoing and other difiiculties of known structures by the provision of an improved relatively simple and the inexpensive drafting apparatus of the protractor type which can be readily adjusted to carry drawing scales at any desired angle and to clamp them in the desired position with substantially no play n the apparatus even after severe and extended use.

Another object of my invention is to simplify and improve mechanism of the indicated type whereby the plate of the protractor mechanism which carries the drawing scales can be locked by quickly releasable spring means in any of a plurality of often-used positions, for example, zero degrees, thirty degrees, forty-five degrees, sixty degrees and ninety degrees.

Another object of my invention is the provision of drafting apparatus of the protractor type having improved bearing structures for the movable parts whereby play in the mechanism is substantially eliminated,

Another object of my invention is the provision of a plate having angular arms associated therewith and adapted to form or-carry the drawing scales, and wherein further the plate has an integral fiat spring associated therewith forlocking the plate and protractor disk together in the various standard positions.

Another object of my invention is to provide a protractor mechanism having a flat spring for locking the plate and disk of the mechanism together, and further, to provide simply, quicklysimple and adjustable vernier mechanism.

Another object of my invention is to provide a pivotal support between the disk and the plate in a protractor drafting apparatus with means for locking, the disk against relative movement with respect to the bolt. forming the pivotal mounting between the plate and disk.

The foregoing and other objects of my invention are achieved by the provision of drafting apparatus including a plate having integral angular arms, a protractor disk, a bolt pivotally connecting the plate and disk, a knob on the bolt for tightening the disk against the plate, means holding the bolt against rotation relative to the disk, and means increasing the clamping diameter of the bolt' and knob on the plate. Completing the combination are means including a spring finger formed integral with the plate in the plane thereof, a tapered pin upstanding from the finger and adapted to engage in any of a series of holes in the disk, means for holding the pin out of engagement with the holes, and a vernier adjustably mounted on the plate.

For a better understanding of my invention reference should be had to the accompanying .30 drawing wherein Fig. 1 is a plan View of a protractor type drafting apparatus embodying the principles of my inveniton; Fig. 2 is a side elevation of the protractor shown in Fig. 1; Fig. 3 is a plan View of the plate forming a part of the apparatus shown in Figs. 1 and 2; Fig. 4 is a fragmentary plan View of the central portion of the protractor disk incorporated in the apparatus; Fig. 5 is a plan view of the keying washer included in the apparatus; Fig. 6 is a fragmentary sectional View through the disk as taken on line VIV| of Fig. 4; Fig. '7 is a side elevation of the bolt included in the assembly; Fig. 8 is a fragmentary plan showing of a modification of the plate assembly shown in Fig. 3; and Fig. 9 is a side elevation of the modified plate assembly shown in Fig. 8.

In the drawing, numeral It indicates, as a whole, a flat metal plate having formed integrally therewith angular arms I2fand l4 which usually are at right angles with each other. The angular arms l2 and i4 may be extended and appropriately engraved with any desired scales as will be understood by those skilled in the art. In addition, I may form the arms I2 and I4 only several inches long and provide them with suitable means to receive any of the standard drawing scales which can be snapped or wedged onto the arms by known devices. In Figs 1 and 2 of the drawing I have shown a drawing scale l6 associated in fixed relation with the angular arm 14.

The plate I is formed with a central aperture l8 adapted to snugly receive a peripherally smooth collar 20 formed integral with a bolt 22 having a large fiat head 24. The collar 20 of the bolt 22 also is received in snug relation in a suitable central aperture formed in a protractor disk 26. The collar 20 is slightly shorter in length than the combined thickness of the plate 10 and disk 26. The protractor disk is provided with the usual degree markings 28 and is formed with means offset from the plane of the disk, as for example a bracket 30, whereby the disk is secured to a system of parallel linkage or the like.

Means are provided to lock the bolt 22 against rotary movement in the disk 26, and to this end, a washer 32 fitting snugly over the threaded portion of the bolt 22 above the disk 26 is formed with an aperture 34 which snugly receives a key or pin 36 fixed on the end of the collar 20 of the bolt 22 so that the axis of the pin 36 is parallel to the bolt axis. Also, the washer is provided with a lug 38 which is adapted to fit tightly in a suitable hole 39 formed in the disk. Ordinarily, the tight or close fit between the lug 38 and its associated hole is accomplished by making the lug 38 tapered so that it will wedge into the hole. The washer 32 therefore acts to lock the bolt 22 against rotary movement relative to the disk 26. A knob 40 threaded onto the bolt 22 serves to clamp the disk 26 and the plate [6 together as will be understood.

I preferably employ means in my protractor mechanism for improving the character of the clamping action effected by the knob 40 and bolt 22. Such means usually takes the form of a raised rib or studs which extend above and below the surface of the disk 26 at a point radially outwardly of the bolt-receiving aperture therethrough. For example, I may employ a plurality of studs 44 of fiber, brass or other material softer than the plate I0, disk 26 and bolt head 24 which are positioned by press-fits in suitable holes extending through the disk 26 at circumferentially spaced points. As best illustrated in Fig. 6, the studs 44 extend above and below the surface of disk 26 and into frictional engagement with the plate [0 and into the frictional engagement with the washer 32. I may make the studs 44 of a self-lubricating bearing material although this is not essential. In all events, the knob 48 when tightened forces the washer 32 into engagement with the studs 44 and the studs in turn are forced into engagement with the plate It]. The result is very effective clutch-like clamping action which operates over a greater diameter than if the studs were not employed and also serves to provide concentrated clamping points adapted to uniform loading. Although I have illustrated and described the studs 44 as positioned in the disk 26 it is obvious that they may be carried instead by the plate H].

An important part of my invention is the provision of relatively inexpensive and simple means for quickly locking the plate ID in any one of a plurality of standard positions. Specifically, I provide a flat spring 50 which is formed integral with the plate I0 and which lies substantially in the plane of the plate. The spring 50 may be of the same piece of metal as the plate III, as

shown in Fig. 3, and may be tempered after being formed to the desired shape. The spring 50 includes an end operating portion 52 which extends radially outwardly of the disk 26 and which is formed vertically offset from the plane of the plate so as to be readily accessible to the user of the apparatus so that the spring can be depressed. The spring 56 carries an upstanding key, usually in the form of a tapered pin 54, made of tungsten carbide or other hard material which is adapted to engage in any one of a plurality of tapered holes 56 formed in the disk 26, so that the plate H] can be locked with respect to the disk at zero, thirty, forty-five, sixty or ninety degrees, or in any other standard or desired positions.

Instead of making the spring 59 and the plate II] from a single piece of material, the spring 53 may be made separate and thereafter secured to the plate as an integral part thereof. For example, in Figs. 8 and 9 I have illustrated a modification of my invention wherein a spring 54:; is riveted or otherwise integrally secured to the plate lEla, as at 66. A bolster plate 62 may be employed between the spring 54a and the heads of the fastening rivets.

In certain instances it is desirable to have the spring 50 held in a non-locking or inoperative position. Of course, any of a plurality of means may achieve this end, and as an example of one such means I provide a small lever 12 which is pivotally mounted, as at 14, on the end of the spring 50 so that a cam surface 16 formed on the lever 12 can be engaged in camming relation under the edge of the disk 26. With the lever 12 in the full line position shown the spring 50 is operative to lock the plate [0 and the disk 26 together in any one of the standard positions. However, when the lever 12 is moved around in a counterclockwise direction (look at Fig. 1) then the cam surface 16 engages underneath the disk 26 to move the spring finger 56 away from the disk 26 so that the pin 54 does not engage with the holes 56 in the disk.

Associated with the disk 26 is an arcuate vernier scale 66 which is formed with arcuate slots 68 adjacent its ends cut on a radius terminating at the center of the bolt 22. Small fastening screws 10 tapped into the plate l0 hold the Vernier scale in its adjusted position on the plate. This construction of the Vernier scale permits it to be adjusted slightly to bring it into proper register with the degree marks 28 on the disk 26 and thus simplifies construction problems.

From the foregoing it will be evident that the objects of my invention have been achieved by the provision of a relatively simple, inexpensive, easily operated and long wearing apparatus of the protractor type. I provide a particularly positive but simple structure for locking the drawing scales of the apparatus in any one of a plurality of standard positions. Further, the mechanism is particularly characterized by large bearing surfaces capable of a smooth and positive clamping action whereby play or movement of the drawing scales after clamping is eliminated for all practical purposes. The clamping action of the apparatus to secure the drawing scales in other than the standard positions is smooth and positive and is concentrated at desired circumferentially spaced points. Also, means are associated with the mechanism for locking the parts in the standard position which means facilitates rendering the standard lock mechanism inoperative. And lastly, I have provided a plate having angular arms associated therewith and an integral spring for effecting the locking of the drawing scales in any one of a plurality of standard positions.

While in accordance with the patent statutes I have particularly illustrated and described one embodiment of my invention, it should be particularly understood that I am not to be limited thereto or thereby, but that the scope of my invention is defined in the appended claims.

I claim:

1. Drafting apparatus comprising in combination a plate having integral angle arms associated therewith and a central bolt aperture, a protractor disk having a central bolt aperture and means adapted to connect the disk to a system of parallel linkage, a plurality of studs of greater length than the thickness of the disk extending through the disk adjacent the aperture and spaced substantially equally there around, said studs having their ends extending a short distance above each side of the disk, a bolt extending upwardly through the plate and disk and having a large flat head, said bolt having an enlarged diameter inside the plate and disk, a pin mounted on the end of the enlarged diameter of the bolt in a position parallel to the bolt axis, a washer over the bolt and engaging with the disk and having a hole receiving the pin, a locking lug on the washer opposite the pin and engaging with a hole in the disk, a knob on the bolt, a spring finger formed integrally with the plate, a tapered key upstanding from the spring finger and engaging in any one of a series of holes in the disk, and means for holding the spring finger so that the key is out of engagement with the locking holes in the disk.

2. Drafting apparatus comprising in combination a plate having angle arms associated therewith and a central bolt aperture, a protractor disk having a central bolt aperture and means adapted to connect the disk to a system of parallel linkage, a plurality of studs of greater length than the thickness of the disk extending through the disk adjacent the aperture and spaced substantially equally there around, said studs having their ends extending a short distance above each side of the disk, a bolt extending upwardly through the plate and disk and having a large flat head, said bolt having an enlarged diameter inside the plate and disk, means for locking the disk against rotary movement relative to the bolt, a knob on the belt, a spring finger formed integrally with the plate, a tapered key upstanding from the spring finger and engaging in any one of a series of holes in the disk, and means for holding the spring finger so that the key is out of engagement with the locking holes in the disk.

3. Drafting apparatus comprising in combination a plate having angle arms associated therewith and a central bolt aperture in the plate, a protractor disk having a central bolt aperture and means adapted to connect the disk to a system of parallel linkage, a plurality of studs of greater length than the thickness of the disk extending through the disk adjacent the aperture and spaced substantially equally there around, said studs having their ends extending a short distance above each side of the disk, a bolt extending upwardly through the plate and disk, said bolt having an enlarged diameter inside the plate and disk, means for locking the disk against rotary movement relative to the bolt, a knob on the bolt, a spring finger formed integrally with the plate, and a key upstanding from the spring finger and engaging in any one of a series of holes in the disk.

4. Drafing apparatus comprising in combination a plate having angle arms associated therewith and a central bolt aperture in the plate, a protractor disk having a central bolt aperture and means adapted to connect the disk to a system of parallel linkage, a bolt extending upwardly through the plate and disk, said bolt having an enlarged diameter inside the plate and disk, a pin mounted on the end of the enlarged diameter of the bolt in a position parallel to the bolt axis, a washer over the bolt and engaging with the disk and having a hole receiving the pin, a locking lug on the washer opposite the pin and engaging with a hole in the disk, a knob on the bolt, a spring finger formed integrally with the plate, and a key upstanding from the spring finger and engaging in any one of a series of holes in the disk.

5. Drafting apparatus including a plate having integral angular arms, a protractor'disk, a bolt pivotally connecting the plate and disk, a knob on the bolt for tightening the disk against the plate,

means holding the bolt against rotation relative to the disk, means increasing the clamping diameter of the bolt and knob on the plate, a spring finger integral with the plate and in the plane of the plate, a tapered pin upstanding from the finger and adapted to engage in any one of a series of holes in the disk, and means for holding the pin out of engagement with holes.

6. Drafting apparatus including a plate having integral angular arms, a protractor disk, a bolt pivotally connecting the plate and disk, a knob on the bolt for tightening the disk against the plate, means holding theh bolt against rotation relative to the disk, means increasing the clamping diameter of the bolt and knob on the plate, a spring finger integral with the plate and in the plane of the plate, and a tapered pin outstanding from the finger and adapted to engage in any one of a series of holes in the disk.

7. Drafting apparatus including a plate having angular arms, a protractor disk positioned above the plate, a bolt pivotally connecting the plate and disk, a knob on the bolt for tightening the disk against the plate, means holding the bolt against rotation relative to the disk, a spring finger integral with the plate and in the plane of the plate, a pin upstanding from the finger and adapted to engage in any one of a series of holes in the disk, and means adapted to connect the disk to a system of parallel linkage.

8. A drafting apparatus of the protractor type including a disk, a plate adapted to have drafting rules associated therewith and pivotally secured to the disk, 3, fiat spring integral at one end with the plate and lying substantially in the plane thereof, and a key outstanding from the spring and adapted to engage in any one of a plurality of holes formed in the disk, said fiat spring and plate being formed from a single piece of metal.

9. A drafting apparatus of the protractor type including a disk, a plate having ruling arms associated therewith, a bolt pivotally securing the plate and disk together, a knob on thebolt for clamping the disk and plate in locked relation, and means associated with the plate and disk for concentrating the clamping pressure at points radially outwardly of the bolt surface and at specific desired circumferentially-spaced areas within the radius of the knob.

10. A 'dra-fting apparatus of the protractor typeincluding a disk, a plate having ruling arms associated therewith, a bolt pivotally securing the plate and disk together, a knob on the bolt for clamping the disk and plate in locked relation, and means of softer material than the disk and carried by the disk extending above and below the surface of the disk adjacent the bolt and adapted to receive the concentrated clamping pressure.

11. A drafting apparatus of theprotractor type including a plate, a disk on top of the plate, a bolt extending upwardly through the plate and disk and pivotally securing the plate and disk together, a key on the bolt, a washer received over the bolt on top of the disk and engaging with the key, and a locking lug on the washer engaging in a hole. in the disk and locking the disk and. bolt against relative rotary movement.

12. A drafting apparatus of the protractor type including a plate, a disk on top of the. plate, a bolt extending upwardly through the plate and disk and pivotally securing the plate and disk together, said bolt having a peripherally smooth collar of enlarged diameter adjacent its head and snugly received in suitable apertures in the plate and disk, a key on the bolt, a washer received over the bolt on topof the disk and engaging with thekey, and alocking lug on the washer engaging in a hole. in the disk and locking the disk and bolt against relative rotary movement.

13. A drafting apparatus of the protractortype including-a plate, a disk on top of the plate, a

bolt extending upwardly through the plate and.

disk and. pivotally securing the. plate and disk together, said bolt having a peripherally smooth collar of enlarged diameter adjacent its head and snugly received in suitable apertures in the plate and disk, and means for locking the disk and the bolt against relative rotary movement.

1 4. A drafting apparatus comprising a disk, a bolt extending through and held. against rotary movement, relative to the disk, a bearing portion on the bolt of larger diameter than the bolt supporting the disk thereon, a plate pivotally mounted. on. the bearing portion of the bolt, friction means carried by the disk and extending above and below the surface thereof, and means on the bolt for clamping against the friction means on one side of the disk and for drawing the plate against the friction means on the other side of the disk.

WALTER J. GREENLEAF. 

